On Tue, 16 Oct 2007 18:44:17 -0700 [email protected] wrote:
> @@ -547,3 +547,41 @@ size is the size (and should be a page-sized multiple).
> The return value will be either a pointer to the processor virtual
> address of the memory, or an error (via PTR_ERR()) if any part of the
> region is occupied.
> +
> +int
> +dma_flags_set_attr(u32 attr, enum dma_data_direction dir)
> +
> +Amend dir with a platform-specific "dma attribute".
> +
> +The only attribute currently defined is DMA_BARRIER_ATTR, which causes
> +in-flight DMA to be flushed when the associated memory region is written
> +to (see example below). Setting DMA_BARRIER_ATTR provides a mechanism
> +to enforce ordering of DMA on platforms that permit DMA to be reordered
> +between device and host memory (within a NUMA interconnect). On other
> +platforms this is a nop.
> +
> +DMA_BARRIER_ATTR would be set when the memory region is mapped for DMA,
> +e.g.:
> +
> + int count;
> + int flags = dma_flags_set_attr(DMA_BARRIER_ATTR, DMA_BIDIRECTIONAL);
> + ....
> + count = dma_map_sg(dev, sglist, nents, flags);
> +
Isn't this rather a kludge?
What would be the cost of doing this cleanly and either redefining
dma_data_direction to be a field-of-bits or just leave dma_data_direction
alone (it is quite unrelated to this work, isn't it?) and adding new
fields/arguments to manage this new functionality?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
